JPH0355924A - Communication equipment - Google Patents

Abstract

PURPOSE:To decrease the number of automatic gain control circuits by providing variable gain amplifier circuits compensating the loss of two IF cables respectively, and one automatic gain control circuit controlling the gain of the variable gain amplifier circuit in common, in either the transmission/reception section or the modulation/demodulation section. CONSTITUTION:When an IF signal is sent from a modulation demodulation section 7 to an input section 8A of a transmission reception section 6, an IF signal inputted to the transmission reception section is amplified by a variable gain amplifier 1 whose output level is controlled to be constant by an automatic gain control circuit(AGC) 2 to compensate the loss by a cable 5. On the other hand, when the IF signal is sent from an output section 9B of the transmission reception section 6 to a modulation demodulation section 7, the IF signal is amplified up to a level to compensate the loss due to the cable 5 in advance by the variable gain amplifier 1, and kept to a specified level in the input section 9A of the modulation demodulation section 7. That is, since the IF cables 5 are of equal length, the level of both the IF cables 5 is compensated by the AGC circuit 2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a communication device, and in particular, a transmitting/receiving section and a modulation/demodulation section are each mounted in separate bodies, and an I/O connection between each section is provided.
The present invention relates to a communication device having an amplifier for compensating for a drop in the level of an IF signal due to cable loss when the F signal is transmitted by two IF cables of equal length.

[Conventional technology]

Conventionally, in this type of communication device, a transmitter/receiver section 20 and a modem section 21 are mounted in separate housings and connected by an IF cable 5 of equal length, as shown in the block diagram of FIG. Here, a variable gain amplifier circuit IO for compensating for a level drop caused by the IF cable 5 and an automatic gain control (hereinafter referred to as AGO) circuit 10 that controls this variable gain amplifier circuit 1l are connected to the input side of the transmitter 3 of the transmitting/receiving section 20, respectively. and was mounted on the input side of the modulation/demodulation section 21 to compensate for the level drop of the equal length IF cable.

[Problem to be solved by the invention]

The configuration of the conventional communication device described above is designed to perform variable gain amplification and AGC control to compensate for the loss caused by the IF signal cable in each part of the transmitting/receiving part and the modulation/demodulation part in separate housings. It has the disadvantage of having duplicate circuits. [Means for Solving the Problems] A communication device of the present invention has a transmitting/receiving section and a modulation/demodulation section each mounted in separate housings, and transmits an IF signal between the transmitting/receiving section and the modulation/demodulation section. Two equal length IFs
In a communication device connected by a cable, the transmitting/receiving device includes variable gain amplifier circuits that compensate for the losses of the two IF cables, and one automatic gain control circuit that commonly controls the gains of the variable gain amplifiers. or the modulation/demodulation section.

On the transmission side of the transmitter/receiver section, a variable gain amplifier and an automatic gain control circuit that controls the variable gain amplifier so that the output level of the variable gain amplifier is constant regardless of the cable length;
On the receiving side of the transmitter/receiver section, it has a variable gain amplifier controlled by an automatic gain control circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

The embodiment shown in FIG. 1 is comprised of a transmitting/receiving section 6, a modulation/demodulation section 7, and two IF cables 5 of equal length. The transmitting/receiving section 6 also includes two variable gain amplifiers IA, IB, an AGC circuit 2,
It is composed of a transmitter 3, a receiver 4, and an IF cable 5.

Although not shown, the variable gain amplifier circuits IA, 1B and the AGC circuit 2 are connected to the input section 9B and the output section 8 in the modulation/demodulation section 7.
There is also a plan to implement it before B. Now, when the IF signal is transmitted from the modulation/demodulation section 7 to the input section 8A of the transmission/reception section 6, the IF signal passes through the cable 5 from the modulation/demodulation section and is input to the transmission/reception section.
The F signal is amplified by a variable gain amplifier 1 controlled by an automatic gain control circuit 2 so that the output level of the variable gain amplifier circuit 1 is constant, and loss due to the cable 5 is compensated for.

On the other hand, the IF signal is transmitted from the output section 9B of the transmitting/receiving section 6 to the modulation/demodulation section 7.
When the IF signal is transmitted to the input section 9A of the modulation/demodulation section 7, the IF signal is amplified by the variable gain amplifier l controlled by the automatic gain control circuit 2 to a level that compensates for the loss caused by the cable 5, and is maintained at a specified level at the input section 9A of the modulation/demodulation section 7. Ru. In other words, since the IF cable 5 has the same length, one AGC
Circuit 2 can compensate the levels of both IF cables 5. [Effects of the Invention] As explained above, the present invention reduces the number of AGC circuits by integrating an AGC amplifier circuit for compensating for level reduction due to cable loss into either the transmitting/receiving section or the modulation/demodulation section. It has the effect of

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional communication device. IA, IB...Variable gain amplifier circuit, 2...
...Automatic gain control circuit (AGC circuit), 3...
Transmitter, 4... Receiver, 5... IF cable, 6... Transmission/reception section, 7... Modulation/demodulation section, 8A, 9A... ...Input section, 8B, 9B...
...Output section.

Claims (1)

[Claims] A transmitting/receiving section and a modulation/demodulation section are each mounted in separate housings, and an I
In a communication device connected by two IF cables of equal length for transmitting an F signal, a variable gain amplifier circuit that compensates for the loss of each of the two IF cables and a gain of the variable gain amplifier are commonly controlled. 1. A communication device comprising: one automatic gain control circuit in either the transmitter/receiver or the modulator/demodulator.